This invention relates in general to fluid seals. More specifically, this invention relates to gaskets that connect two sealing portions, which prevent fluid leakage between the two, while reducing the transmission of vibrations through the gasket.
In general, conventional gaskets require a relatively high compressive load between the members being sealed in order for the gasket to provide an effective seal. For example, a gasket placed between two stationary members, such as an engine block and an oil pan, or an engine cylinder head and a valve/cam cover, is compressed between these elements. However, while producing an effective seal, these highly compressed gaskets can become a medium for transmitting vibrations, creating poor noise, vibration and harshness (NVH) isolation characteristics between the two members. That is, the vibration load input from one member is easily transferred through the gasket to the other member. Moreover, in these applications that require the high compressive sealing load, the number and placement of fasteners must compensate for deflections caused by the high loading conditions in order to assure a good seal all of the way around the gasket.
Examples of such conventional gaskets requiring a high sealing load between the members include an elastomeric gasket, shaped as an O-ring or similar shape, as well as an edge bond gasket, a carrier gasket, and a rubber coated metal (RCM) gasket. All of these conventional gaskets require a high compressive sealing load to assure an effective seal between the members, so the effectiveness of vibrational isolation of one member from the other is poor. Another example of a conventional gasket is one formed from a room temperature vulcanite (RTV) located between the two members. The RTV is applied as a liquid in a thin layer and cures when exposed to air. For effective sealing with the RTV, however, it requires a hard mount between the members, which also provides poor vibration isolation.
In many applications, including automotive applications, it is desirable to reduce the transmission of vibrations. A reduction of the transmission of vibrations can result in a reduction in noise and harshness, so it is desirable to reduce the transmission of vibrations between two sealed elements, such as an engine block and an oil pan—or engine head and rocker/cam cover.
Thus, it is desirable to have a gasket that will properly seal between two members while allowing for vibration isolation between the two members.